The purpose of the proposed research will be to elucidate the mechanism of action of female sex hormones on tissues of the oral cavity. The specific objectives of this project have been divided into three parts. Phase 1 will determine the optimum conditions under which the presence of hormone "receptors" in non-target tissues could be detected. The search for these "receptors" will be conducted in Phase 2. In addition, Phase 1 will explore the role played by histamine in the oral tissue's response to female sex hormones. Phase 3 will test the human female gingival tissues for "receptor" proteins, and correlate these findings with clinical and histological observations. Phase 1 will utilize the incorporation of radioactive precursors to determine the time course of DNA and protein synthesis in the cheek pouches of the ovariectomized female hamsters. The cheek pouches of all animals will be insulted (stripped) to promote tissue repair and experimental animals will be under systemic hormonal influence. Phase 2 will use a DEAE-cellulose filter assay technique to detect "receptor" protein-radioactive hormone complexes in target and non-target tissues. Similar methods will be employed in Phase 3 to determine whether or not "receptor" proteins are present in human female gingival biopsies.